We're going to begin with the Georgia father charged with murder, for leaving his 22-month-old son in a blistering hot car. The dad will be in court this afternoon. The evidence is eye-opening. Dan and Nancy standing by. They're going to weigh in on all of this. Let's begin with Steve osunsami. Reporter: Today, the lead investigator in this case is going to explain in court why police believe the death of cooper Harris was murder, not an accident. Cooper died after seven hours in his father's hot SUV June 18th. Police say the father, Ross Harris, told them he forgot to drop his son off at a day care near his office that morning. Police reports say Harris told them he discovered his son, cooper, strapped in his car seat when he left work that evening. At his first court appearance, 33-year-old Harris showed little emotion. And pleaded not guilty to murder and second-degree cruelty. His family calling this is tragic mistake. But according to a police warrant, Harris did access the same vehicle, through the driver's side door to place an object into the vehicle. He closed the door and left the car. In the warrants, police also say both of the boys' parents searched the internet for information on child heat stroke inside cars before their son died. The father claimed he was fearful this could happen. The mother has not been charged with a crime. It matters. Timing and context. If it was done 24 hour, 48 hours before the incident, too coincidental. If it was done weeks in advance, it may be related to an event that had been on the news or had been on the internet about the death of another child. Reporter: At her son's funeral in Alabama, Leanna Harris stood by her husband, who joined the services by speakerphone. She called her husband a great father. And told mourners she will miss her son forever. She said no one loved and worshiped the boy more than his father. For "Good morning America," Steve osunsami, ABC news, Atlanta.

This transcript has been automatically generated and may not be 100% accurate.

Georgia Father Charged With Murder in Toddler's Hot Car Death

Justin Ross Harris says he accidentally left his son in the car for seven hours on a 90-degree day.

Premeditation Considered in Georgia Infant's Hot Car Death

A look at the parent's Internet search histories has raised questions about the toddler's death.

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